1. Field of the Invention
The present invention relates to a method for recognizing characters on a document image captured by a camera and saving recognized characters. Particularly, the present invention relates to a method for recognizing characters on a name card image captured by a mobile camera phone with an internalized or externalized camera and automatically saving the recognized characters in corresponding fields of a predetermined form such as a telephone directory database.
2. Description of the Related Art
An optical character recognition (OCR) system or a scanner-based character recognition system has been widely used to recognize characters on a document image. However, since these systems are dedicated system for recognizing characters on a document image, massive applications and hardware sources are required to process and recognize the document image. Therefore, it is difficult to simply apply the character recognition method used in the OCR system or scanner based recognition system to a device having a limited process and memory. A mobile camera phone may be designed to recognize the characters. That is, the camera phone is used to take a picture of a small name card, recognize the characters on the captured image, and automatically save the recognized characters in a phone number database. However, since the mobile camera phone has a limited processor and memory, it is difficult to accurately process the image and recognize the characters on the image.
Describing a method for recognizing a name card using the mobile camera phone in more detail, a name card image is first captured by a camera of the mobile camera phone and the characters on the captured card image are recognized by fields using a character recognition algorithm. The recognized characters are displayed by fields such as a name, a telephone number, an e-mail address, and the like. Then, the characters displayed by fields are corrected and edited.
The corrected and edited characters are saved in a predetermined form of a phone number database.
Generally, when a user receives names cards from customers, friends and the like, the users opens a phone number editor of his/her mobile phone and inputs the information on the name card by himself/herself using a keypad of the mobile phone. This is troublesome for the user. Therefore, a mobile camera phone having a character recognizing function has been developed to take a picture of the name card and automatically save the information on the name card in the phone number database. That is, a document/name card image is captured by an internalized or externalized camera of a mobile camera phone and characters on the captured image are recognized according to a character recognition algorithm. The recognized characters are automatically saved in the phone number database.
However, when a relatively large number of characters are existed on image capture by the camera or scanner, since the mobile phone has a limited process and memory source, a relatively long process time is taken even when the recognition process is optimized. Furthermore, when the characters are composed in a variety of languages, the recognition rate may be deteriorated as compared with when they are composed in a single language.
FIG. 1 shows a schematic block diagram of a prior mobile phone with a character recognizing function.
A mobile phone includes a control unit 5, a keypad 1, a display unit 3, a memory unit 9, an audio converting unit 7c, a camera module unit 7b, and a radio circuit unit 7a. 
The control unit 5 processes data of a document (name card) image read by the camera module unit 7b, output the processed data to the display unit 3, processes editing commands of the displayed data, which are inputted by a user, and save the data edited by the user in the memory unit 9. The keypad 1 functions as a user interface for selecting and manipulating the function of the mobile phone. The display unit 3 displays a variety of menu screens, a run screen and a result screen. The display unit 3 further displays an interface screen such as a document image data screen, a data editing screen and a edited data storage screen so that the user edits the data and save the edited data. The memory unit 9 is generally comprised of a flash memory, a random access memory, a read only memory. The memory unit 9 saves a real time operating system and software for processing the mobile phone, and information on parameters and states of the software and the operating system and performs the data input/output in accordance with commands of the control unit 5. Particularly, the memory unit 9 saves a phone number database in which the information corresponding to the recognized characters through a mapping process.
The audio converting unit 7c processes voice signal inputted through a microphone by a user and transmits the processed signal to the control unit 5 or outputs the processed signal through a speaker. The camera module unit 7b processes the data of the name card image captured by the camera and transmits the processed data to the control unit 5. The camera may be internalized or externalized in or from the mobile phone. The camera is a digital camera. The radio circuit unit 7a functions to connect to mobile communication network and process the transmission/receive of the signal.
FIG. 2 shows a block diagram of a prior name card recognition engine.
A prior name card recognition engine includes a still image capture block 11, a character-line recognition block 12, and application software 13 for a name card recognition editor.
The still image capture block 11 converts the image captured by a digital camera 10 into a still image. The character line recognition block 12 recognizes the characters on the still image, converts the recognized characters into a character line, and transmits the character line to the application software. The application software 13 performs the name card recognition according to a flowchart depicted in FIG. 3.
A photographing menu is first selected using a keypad 1 (S31) and the name card image photographed by the camera is displayed on the display unit (S32). A name card recognition menu for reading the name card is selected S33. Since the recognized data is not accurate in an initial step, the data cannot be directed transmitted to the database (a personal information managing data base such as a phone number database) saved in the memory unit. Therefore, the name card recognition engine recognizes the name card, coverts the same into the character line, and transmits the character line to the application software. The application software supports the mapping function so that the character line matches with an input form saved in the database.
The recognized name card data and the editing screen is displayed on the display unit so that the user can edits the name card data and performs the mapping process (S34 and S35). The user corrects or deletes the characters when there is an error in the character line. Then, the user selects a character line that he/she wishes to save and saves the selected character line. That is, when the mapping process is completed, the user selects a menu “save in a personal information box” to save the recognized character information of the photographed name card image in the memory unit (S36).
FIGS. 4 and 5 show an example of a name card recognition process.
FIG. 4 is an editing screen by which the user can corrects or deletes the wrong characters when the user finds the wrong characters while watching the screens provided in the steps S34 and S35. In the editing screen, the user moves a cursor to a wrong characters “DEL” 40 to change the same to a correct characters “TEL”. After the editing is finished, the user selects only character lines that he/she wishes to save in the database and saves the same in the memory unit. For example, as shown in FIG. 5, when a job title of the name card is “Master Researcher,” the line “Master Researcher” 50 is blocked and a field “title” 61 is selected in a menu list 60. Then, the mapping process is performed to save the “Master Researcher” that is a recognition result in a title field of the database.
In order to improve the recognition rate of the mobile phone, a clear, correct document image data (a photographed name card image data) must be provided to an input device of the character recognition system. In addition, the most efficient recognition can be realized while minimizing the load of the limited sources such as the processor and memory of the mobile phone.
In order to recognize the characters on the name card image captured by the camera, the name card image is first binary-coded and a field required by the user is selected from the binary-coded image and saved in the memory unit. At this select, since the binary-coding process is performed even for an unnecessary portion of the name card image, the recognition efficiency is deteriorated. Particularly, since the character recognition and the field selection are performed after the binary-coding process for all of the name card image is performed, the manipulation frequency of the mobile phone is increased, thereby deteriorating the user-convenience.